The present invention relates to a method of exterminating termites and similar harmful insects living in, or traversing the area under a house or building. More specifically, this invention relates to a method of exterminating harmful insects in which insecticide effectively adheres to all exposed surfaces in the area under the house or building. For the purposes of this patent application the meaning of the word insecticide encompasses substances which deter insect presence as well as substances which kill insects.
Application of insecticide under buildings and houses to exterminate termites is currently performed, and has been performed in the past. Former methods require workers to wear totally protective clothing, gloves, and gas masks, crawl under the building, and disperse chlordane or other insecticides over the entire exposed ground and/or coat wooden beams such as the groundsills with insecticide.
These former methods of applying insecticide are not only extremely laborious, but also require exterminators to work for long periods in the confined area under a building while breathing poisonous insecticide fumes. Hence, the work environment is extremely bad. Furthermore, these methods have the drawback that complete insecticide coverage in very cramped areas is impossible. Some houses and buildings have very small, confined regions that cannot be reached to apply insecticide.
In particular, it is extremely difficult for a worker, inside the area under a building, to apply insecticide with a brush or similar applicator in narrow gaps such as those between the floor boards. It is possible to apply liquid insecticide to the gaps and crevices even in confined areas by spraying. However, with this method atomized droplets of the sprayed insecticide float in the air under the building, and unfortunately, gas masks can not completely eliminate the poisonous particles. Hence, working conditions are made worse by making the worker breathe insecticide droplets. For the worker's protection, liquid insecticide application is restricted to organophosphate type insecticides with dispenser pressures of 5 Kg./square cm. and below. It is impossible for exterminators to work for long periods in this type of hazardous environment, and it is therefore impossible to entirely cover the area under a building with insecticide by these methods.
In cases where total coverage is impossible, termites will establish a route into the home or building through the area where insecticide has not been applied. For example, even though the area under a building may be almost entirely covered with insecticide, one uncovered area will drastically reduce the extermination effectiveness within the entire building.
By former methods where workers enter the enclosed area under a building and disperse and/or apply insecticide with a brush, not only is it impossible to entirely cover all the exposed surfaces, but it is clearly impossible to apply insecticide in all the narrow crevices, as well as open areas exposed only through narrow crevices.
For these reasons, recently adopted methods of insecticide application basically involve coating the entire surface of the ground under the building with organic salt type insecticides such as chlordane, which do not degrade easily, and hence remain effective for extremely long periods. These methods take advantage of the ease of application to the ground surface, and prevent insect penetration at that point.
However, it is presumed that these techniques may bring about serious environmental pollution problems in the future, and the use of chlordane has been outlawed in Japan.
As mentioned, insecticides like chlordane have the special attribute that they remain on or in the ground without degrading, and hence provide long term effectiveness against harmful insects. On the other hand, it is impossible to keep the insecticide within the area under the building forever, and the substance inevitably seeps into the ground water along with rain water to pollute plants and vegetables, domestic animals which feed on the plants, and humans that eat the plants and animals. According to recent reports, chlordane has been detected even in animals of the south pole, which is assumed to be the most unpolluted location on earth.
It has recently been proposed that organophosphates be used instead of organic salt type insecticides. Organic salt type insecticides gradually accumulate in the human body over a long period, and when the accumulated quantity exceeds a critical value, severe impairment results without warning. By the time symptoms are recognized, it is too late for treatment, and recovery is impossible. Conversely, even a small quantity of organophosphate type insecticide attached to the skin or breathed into the body has a strong poisonous reaction which can be immediately treated. However, even though treatment can normally be performed in time, since organophosphates are extremely poisonous to humans, workers must take preventive measures that would not even be considered using chlordane. During the application of organophosphates, people in the vicinity of the house or building as well as those in the building must be evacuated, and particular care must be taken to insure that atomized insecticide does not leak out of the enclosed area under the building.
An ideal harmful insect extermination method could be realized with an insecticide which degrades rapidly in the ground yet has sufficient strength to exterminate insects. Unfortunately, since such insecticides are applied to the ground, they loose effectiveness rapidly, and long term effective harmful insect extermination is impossible.
The inventor proposed that workers remain outside the area under the building, and that harmful insect penetration into the building be stopped at the foundation, the groundsills, the support beams, the floor beams, and the floor boards, rather than at the ground. With this in mindhe has experimented with various application methods.
The first experiment attempted to obtain complete coverage by spraying liquid insecticide, atomized by compressed air pressure, from a nozzle inserted into the area under the building. Although insecticide coverage by this method was obtained in the vicinity of the nozzle, complete coverage of all the exposed surfaces in the enclosed area under the building could not be accomplished. The inventor performed many experiments varying the nozzle shape, the nozzle opening size, the compressed air pressure, etc., but was unable to realize complete adhesion of insecticide in the area under the building.
In further experiments applying different methods, the inventor was able increase the specific gravity of ejected particles of a solid insecticide in powdered form, independent of the compressed air pressure, and accelerate uniformly sized particles to a high ejection velocity using high air pressures. Further, by unidirectional acceleration of the body of ejected particles the inventor was successful in adhering insecticide to all surfaces, crevices, and areas accessible only through narrow crevices, from outside the enclosed area under the building, to a degree unimaginable by former methods.
Unfortunately, this method has the drawback that most of the insecticide sprayed into the area under the building floor falls to the ground and the insectide's effectiveness is thereby reduced.
The effectiveness of the insecticide can be increased by adjusting its adhesive properties. For example, adhesion can be improved by spraying a mixture of insecticide and bonding adhesive compound This method has the drawbacks that a complicated sprayer configuration is required to simultaneously eject insecticide and adhesive, and excessive labor is required to handle these substances and complex equipment. Another drawback results from the demand for a bonding adhesive compound having special properties that allow it to be sprayed as a liquid in unhardened form, and that allow it to harden such that the effectiveness of the insecticide is not reduced by adhesive encapsulation. Namely, it is difficult to select the proper adhesive and insecticide mixture ratio, the proper adhesiveness, and the proper chemical variety of bonding adhesive compound for spraying. A further drawback arises from laborious cleanup procedures which require complete removal of all insecticide and adhesive mixture from the spraying system, as well as drying the cleaned parts.
The inventor investigated the possibility of improving the adhesiveness of the insecticide by adjustment of the physical properties of the insecticide substance. Fortunately, investigation showed that almost without exception the insecticides used had a high electrical resistance and their adhesiveness could be improved with a static electric charge.
Technology for charging airborne floating particles has been previously developed for static electric dust collecting equipment. By these methods, several thousand volts is established between two thin parallel wires, and particulates passing through the interval between the wires are charged by a weak electrical discharge in that interval. This technique can be used to electrically charge an insecticide by arranging two thin wires charged with a high voltage at the exit of the insecticide spray nozzle. Adhesive strength obtained by charging the insecticide with static electricity allows effective coating of all the exposed areas under the building, and in particular allows effective adhesion of insecticide to vertical surfaces as well as to the underside of the floor. Insecticide having the adhesive strength to attach to the underside of the floor can completely coat all surfaces producing outstanding pest extermination and deterance.
However, this method requires the use of several thousands of volts of electricity, and is therefore a relatively dangerous operation. Handling procedures are complicated by the necessity to avoid electrical shock, and a high voltage power supply is required making the spraying equipment very expensive.
It is a major objective of this invention to develop a method of exterminating insects under the floor of a house or building, which overcomes the above drawbacks and increases the insecticide's pest extermination effectiveness by forcibly coating all exposed surfaces using an extremely simple method of charging the insecticide with frictional static electricity thereby eliminating the need for an insecticide charging power supply or particularly expensive spraying equipment.
Another major objective of this invention is to provide a highly effective method of exterminating insects under the floor of a house or building, by which all exposed surfaces can be completely covered with insecticide applied by a simple procedure by workers outside the area under the building.
A further major objective of this invention is to attach insecticide to, and completely cover the foundation, groundsills, support beams, floor beams, and floor boards, thus allowing extermination using insecticides which degrade in the ground over a short period, and thus drastically reducing environmental pollution.
Still another major objective of this invention is to apply insecticide without requiring workers to enter the enclosed area under the building, thus allowing application even under low to the ground floors where workers cannot enter, as well as greatly improving working conditions by avoiding insecticide ingestion.
Another major objective of this invention is to use compressed air pressure to accelerate insecticide into the enclosed area under a building without introducing large quantities of air, and hence, to minimize the leakage of insecticide outside of that area during application.